S3C9442 Datasheet, PDF (47/50 Pages) Samsung semiconductor – SAM88RCRI family of 8-bit single-chip CMOS microcontrollers

S3C9442/C9444/F9444/C9452/C9454/F9454
SAM88RCRI INSTRUCTION SET
SUB — Subtract
SUB
Operation:
dst,src
dst ← dst – src
The source operand is subtracted from the destination operand and the result is stored in the
destination. The contents of the source are unaffected. Subtraction is performed by adding the
two's complement of the source operand to the destination operand.
Flags:
C: Set if a "borrow" occurred; cleared otherwise.
Z: Set if the result is "0"; cleared otherwise.
S: Set if the result is negative; cleared otherwise.
V: Set if arithmetic overflow occurred, that is, if the operands were of opposite signs and the sign of
the result is of the same as the sign of the source operand; cleared otherwise.
Format:
opc dst | src
Bytes Cycles
2
4
6
Opcode
(Hex)
22
23
Addr Mode
dst src
r
r
r
lr
opc
src
dst
3
6
6
24
R
R
25
R
IR
opc
dst
src
3
6
26
R
IM
Examples:
Given: R1 = 12H, R2 = 03H, register 01H = 21H, register 02H = 03H, register 03H = 0AH:
SUB
SUB
SUB
SUB
SUB
SUB
R1,R2
→
R1,@R2 →
01H,02H →
01H,@02H →
01H,#90H →
01H,#65H →
R1 = 0FH, R2 = 03H
R1 = 08H, R2 = 03H
Register 01H = 1EH, register 02H = 03H
Register 01H = 17H, register 02H = 03H
Register 01H = 91H; C, S, and V = "1"
Register 01H = 0BCH; C and S = "1", V = "0"
In the first example, if working register R1 contains the value 12H and if register R2 contains the
value 03H, the statement "SUB R1,R2" subtracts the source value (03H) from the destination
value (12H) and stores the result (0FH) in destination register R1.
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